Opposed gating injection method

ABSTRACT

The foregoing objects are attained by the opposed gating injection method and apparatus for forming molded articles and for use with injection molders wherein a first mold half and a second mold half are adapted to cooperate and form at least one mold cavity. A first injector nozzle is positioned in a first mold half adjacent the cavity, for injecting a first molding resin into the cavity through a first orifice. A second injector nozzle is included which is positioned in the second mold half adjacent the cavity for injecting a second molding resin. The second resin may be different from the first resin or the same as the first resin. The second resin is injected through a second orifice unconnected with the first orifice. The injector nozzles may be either simultaneously or sequentially activated for filling the mold cavity, and may be single material or co-injection type nozzles.

This is a Division of application Ser. No. 08/254,139, filed Jun. 6,1994, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to injection molding, and more particularly, toan improved apparatus and method for facilitating space efficientinjection molding using opposed nozzles.

The method of co-injection is characterized by injecting a first resininto a mold cavity, followed by, or simultaneously with, the injectionwith one or more other resin types into the same cavity. This methodtypically results in the article having multiple layers across itscross-section and generally a greater number of layers than resin typesin the case where sequential injection of the resins is used.

The injection art includes a multitude of apparatuses and processes forforming molded articles from multiple resins by co-injection. Forexample, U.S. Pat. Nos. 5,028,226 and 4,717,324, show simultaneous andsequential co-injection apparatuses and methods, respectively. Bothpatents show one nozzle dedicated to a mold cavity wherein the moldcavity is completely filled for molding purposes by injecting amultitude of resins through a single gate orifice. Because a singleorifice is used for the multitude of resins, the hot runner systememployed to receive the various resin types from the resin source forconveyance to the molded cavities can be very complicated, as evidencedin the figures shown in the two patents. As a result, such complicatedhot runner systems lead to mold designs which are not compact andthereby allow fewer cavities and fewer articles to be molded within agiven space on a molding machine. Because of their complexity, thesystems also require special design and manufacturing attention notnormally required or encountered with less demanding one resin injectionsystems.

An alternative co-injection process is shown in U.S. Pat. No. 4,803,031,where molded articles are formed by injecting one resin into a cavityand filling the cavity space, and thereafter enlarging the cavity andfilling the additional space with a second resin. The result of such atechnique is two distinct areas each comprised of a resin type. However,such an arrangement requires two injection points into the mold cavity,resulting in complicated and bulky hot runner designs. As can be seen inthe figures, the design of the hot runners dictate wide spacing of thecavities and are in themselves of a complicated non-rectilinear design.U.S. Pat. No. 4,275,030 suffers from these same problems, disclosing asimilar method of producing a molded article from multiple resins. Inthis patent, the mold cavities are partitioned by movable blades, andresin is injected into a first partitioned portion of the cavity. Theblade is then moved and resin is injected into the remaining portion ofthe cavity through an additional nozzle orifice. As a result, thedifferent resin types are caused to join or weld at the area formallyoccupied by the blade.

U.S. Pat. No. 3,873,656 shows a co-injection apparatus wherein amultitude of plastics are injected into a mold cavity through a numberof different gates. The timing of the opening and closing of the gatesdictates the amount and extent of the resin types which form the moldedarticle. As can be seen from the figures, the design is only suitablefor molding very large plastic articles, wherein the multitude of gatescan be used. Also, the hot runner shown does not have the capability forallowing individual temperature control of the different resin types,which inherently limits the variety of resins which can be used in thesystem together. In addition, since the gates are apart from oneanother, the flow of each resin will not be symmetrical throughout thepart but instead will be biased in the area of the injection orifice.

U.S. Pat. No. 4,212,626 discloses an apparatus and method fortransferring plastic in a stack mold arrangement. Two melt injectionunits are used, one unit is located in the stationary platen of thestack mold and the other unit is located in the movable platen of thestack mold. Each unit has its own runner passage and its own flowcontrol gate. When the movable platen is in the closed position, againstthe stationary platen, the gates of each unit are in conductingcommunication. Accordingly, the gate of each unit is actuated to openand close when the platen is in the closed position in order to providea flow of pressurized melt from the first runner passage to the secondrunner passage. The apparatus disclosed is not designed for use with twomaterials. One hot runner is provided for feeding a plurality ofcavities from one nozzle. The hot runner passes through separate controlvalves and progressively moves plastic to each cavity. With only one hotrunner providing materials to all cavities, only one material can beused to mold the articles.

U.S. Pat. No. 5,145,630 discloses a method and apparatus for improvedcore/cavity alignment in the production of a monomaterial thin walledcontainer. This apparatus is used to inject plastic into the rim portionof a thick lipped article for stabilizing the position of the mold corewith respect to the cavity during the process of plastic injection. Inthe embodiment shown in FIG. 4, simultaneous injection of plastic fromopposite ends of the container is shown. The purpose of the simultaneousinjection is apparently to stabilize the core shift by reducing plasticflow length through the thin wall section. As a result, more uniformflow is established. The apparatus disclosed is directed only for usewith a single resin.

Hence, there exists a need in the injection molding art for a simplifiedmold design which allows for efficient positioning of nozzles andefficient space use, for the injection of a plurality of resins.

SUMMARY OF THE INVENTION

The primary object of this invention is to provide a system and methodfor injecting multiple resins into a mold cavity in a space efficientmanner.

Another object of this invention is to provide an injection system andmethod which uses simple nozzle and hot runner designs.

Yet another object of this invention is to provide an injection systemand method wherein hot runners and nozzles can be independently adjustedfor each resin, while being space efficient for placement in the mold.

Still another object of this invention is to provide an injection systemand method which is simple in construction and can produce parts withunique qualities.

And still another object of this invention is to provide a spaceefficient single material injection system for efficiently molding aplurality of articles in a multi-cavity mold.

The foregoing objects are attained by the inventive opposed gatinginjection method and apparatus of the instant invention which is used inthe main embodiment, for forming molded articles from a composite ofmaterials with injection molders having a first mold half and a secondmold half adapted to cooperate to form at least one mold cavity. Theinvention includes a first injection means positioned in the first moldhalf adjacent the one cavity for injecting a first molding resin intothe mold cavity through a first orifice. A second injection means isincluded which is positioned in the second mold half adjacent the moldcavity for injecting a second molding resin. The second molding resinmay be different from or the same as the first resin. The second resinis injected through a second orifice unconnected with the first orifice.In accordance with the invention, the injection means may be eithersimultaneously or sequentially activated for filling the mold cavity.

Another embodiment of the invention includes a first injection means forinjecting a first material in a first mold cavity. The first injectionmeans is positioned in the first mold half. A second injection means isincluded for injecting the first material in a second mold cavityunrelated to the first mold cavity. The second injection means ispositioned in the second mold half, wherein the first and secondinjection means are relatively positioned in an offset manner.

An injection process for the main embodiment includes forming a moldedarticle from a composite of materials which includes the step ofproviding an injection molder having first and second mold halvesadapted to cooperate to form at least one mold cavity for forming themolded article. Additional steps of the process include injecting afirst material into the mold cavity from a position within the firstmold half and injecting a second material into the mold cavity from aposition within the second mold half, wherein the second material isdifferent from the first. The process may include the steps of injectingeither being sequential or simultaneous, wherein the selected styledictates the type of layered arrangement comprising the final moldedarticle.

The first embodiment of the invention may include the first injectionmeans being a first injection nozzle positioned in an opening within thefirst mold half of the injection molder. The same embodiment may includethe second injection means being a second injection nozzle positioned inan opening within the second mold half, wherein the materials from thefirst and second nozzles are distributed in the cavity formed by themold halves. The same embodiment may also include each injection nozzlehaving a separate material source wherein the sources for each nozzleare unconnected. Alternative embodiments of the invention may alsoinclude the nozzles substantially opposing each other or in an offsetarrangement.

The details of the present invention are set out in the followingdescription and drawings wherein like reference characters depict likeelements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional elevational view of an injection apparatusin accordance with the principles of the present invention.

FIG. 2 is an enlarged view of FIG. 1, showing the first injection stepof a sequential injection process.

FIG. 3 is similar to FIG. 2, showing the second injection step of thesequential injection process.

FIG. 4 is a cross-sectional view of the injection apparatus and methodof the instant invention used in a multi-cavity mold.

FIG. 5 is a cross-sectional view showing the results of simultaneousinjection.

FIG. 6 is a cross-sectional view showing the results of usingsimultaneous injection and combining a high viscous and low viscousresin.

FIGS. 7 and 8 are cross-sectional views showing the injection apparatusbeing used with a movable core for forming a multi-layered article.

FIGS. 9 and 10 are cross sectional views showing the injection apparatusand a process of using a sheet material for imprinting or dividing themolded article.

FIGS. 11 and 12 are cross-sectional views showing an alternativeembodiment of this invention wherein the nozzles are offset from eachother.

FIGS. 13 and 14 are cross-sectional views of the offset nozzleembodiment using a non-uniform mold.

FIG. 15 is a cross sectional view showing another embodiment of thepresent invention using multiple offset nozzles.

FIG. 16 is a cross-sectional view of another alternative embodimentshowing the use of a singular nozzle positioned in one mold half and aco-injection nozzle positioned in the other mold half.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing in detail, there is shown in FIG. 1 across-sectional elevation view of the opposed gating injection moldingdevice of the present invention, designated generally as 10. Device 10is used to form an article 12 between a female mold half 14 having amolding surface and a male mold half 16, having a molding surface,wherein female mold half 14 is connected with a stationary platen 18 andmale mold half 16 is connected with a moving platen 20. Female mold half14 cooperates with male mold half 16 to form a mold cavity 22.

As shown in FIG. 1, device 10 includes an injection assembly 24positioned in female mold half 14 and stationary platen 18 and aninjection assembly 26 positioned in male mold half 16. Injectionassembly 24 includes nozzle 28 and injection unit 30. Nozzle 28 ispositioned in female mold half 14 adjacent mold cavity 22 such thatorifice 32 opens into cavity 22. Injection unit 30 is in flowcommunication with a source (not shown) for resin or material 34 whichis forcibly injected into cavity 22 via nozzle 28 and injection unit 30.Similarly, injection assembly 26 includes nozzle 36, injection unit 38,and in addition, a melt flow manifold 40. In this embodiment, nozzle 36is positioned in male mold half 16 essentially opposite the positioningof nozzle 28 in female mold half 14, adjacent mold cavity 22.Accordingly, nozzle orifice 42 opens into mold cavity 22 for depositinganother resin or material 44 therein during the injecting moldingprocess.

As shown in FIG. 1, assembly 26 is positioned in a different manner thanassembly 24. That is, injection assembly 24 in female mold half 14 isarranged such that injection unit 30 is positioned on the samehorizontal plane as nozzle 28, such that they are substantially in line.However, because assembly 26 uses a manifold 40 for heating resin 44prior to its entrance into nozzle 36, and for horizontal space savingreasons, injection unit 38 is positioned substantially perpendicular toand spaced vertically from nozzle 36. As a result, vertical space isused in supporting elements of the device as opposed to having toincrease the horizontal dimensions of the molder.

Referring now to FIG. 2, a molded article can be formed from acombination of different resins, 34 and 44, wherein each resin isseparately introduced into cavity 22 from opposing nozzles 28 and 36. Asshown in FIG. 2, first resin 34 is first introduced into cavity 22through nozzle 28 and partially fills the central portion of cavity 22.Subsequently, second resin 44 is introduced into cavity 22 throughnozzle 36 wherein the mold cavity 22 becomes filled with resins 34 and44 in the manner as shown in FIG. 3. As a result of this sequentialinjection process, firstly introduced resin 34 is forced to the edges ofmold cavity 22 via resin 44. An article 12, as shown in cavity 22 ofFIG. 3, is formed wherein resin 34 forms the exterior of article 12 andresin 44 forms the interior of article 12.

By the arrangement shown in FIGS. 1-3, the simplified injectionassemblies shown can each have independent and precise temperaturecontrols particularly compatable with each resin, thereby simplifyinghot runner construction. Additional controls 45, shown schematically inFIG. 1, for selecting simultaneous or sequential injections from thenozzles are also implemented with device 10.

Referring now to FIG. 4, the arrangement as shown in FIGS. 1-3 can bemodified for use in a multi-cavity mold for the production of amultitude of composite material parts, typically small closures. Device110 is used for forming a multitude of articles 112 in a singleinjection molding step. A device comprises a plurality of nozzles 136positioned in male mold half 116 and a plurality of opposinglypositioned nozzles 128 positioned in female mold half 114. Nozzles 128are fed by injection unit 130 and nozzles 136 are fed by injection unit138. Again, because of the lesser availability of horizontal space,injection unit 138 is positioned out of line with nozzles 136 as opposedto injection unit 130 being in line with nozzles 128. Injection unit 130forcibly moves a first resin into nozzles 128 via a common feed area 150having a plurality of feed branches leading to each nozzle. Similarly,injection unit 138 feeds a second resin into nozzles 136 via a commonfeed area 152 which has feed branches leading into nozzles 136. As aresult of the opposing nozzles, the spacing between cavities 122 can bevery tight so that a high number of closures can be produced within agiven space available for molding. Hot runner manifolds 154 and 156supporting nozzles 128 and 136, respectfully, are inherently isolatedfrom each other, leading to precise temperature control and melt channelflow paths optimally configured for each resin type without interferencefrom the requirements of other resins. Accordingly, manifolds 154 and156 and nozzles 128 and 136 can be of the standard variety which arenormally used for making articles requiring only a single material.

Various processes of resin injection can be used with the twoembodiments shown in FIGS. 1-4. Referring to FIG. 5, if instead of usinga sequential injection as discussed above in FIGS. 1-4, a simultaneousinjection process is used, a two-layered instead of a three-layeredarticle comprising two resin materials can be formed. FIG. 5 showsresults of simultaneously injecting different resins 34 and 44 fromnozzles 28 and 36, respectively. In addition to the simultaneousinjection, the fine tuning of material volume and velocity from each ofthe nozzles can produce different outcomes in the characteristics of themolded article.

Referring now to FIG. 6, if materials having different viscosities areused, an even different result in article 12 can be achieved. FIG. 6shows a high viscosity material 52 being ejected from nozzle 36 and alow viscosity material 54 being ejected from nozzle 28. As a result ofthe slower flow into cavity 22 by low viscosity material 54, theresultant article exhibits a thin wall and a thick wall, wherein thethin wall is comprised of the slower entering low viscosity material 54.In addition, parameters such as velocity, pressure and timing can bevaried to mold articles having desired performance or visualcharacteristics which are dictated by the material thicknesses of thearticle.

In addition to the above parameters, if mold cavity shapes are alteredand mold half movements are performed, uniquely layered and configuredarticles can be achieved. Referring now to FIGS. 7 and 8, for example,male mold half 16 is shown having a mold core 55 having a groovedperiphery and a recessed end for achieving a threaded closure uponcooperation with female mold half 14. As shown in FIG. 7, female moldhalf 14 is positioned such that it abuts the end of core 55, formingcavity 22a with the recessed end. At this juncture, a first material canbe injected into cavity 22a, for filling the same with first material 44from nozzle 36 in mold core 55, as shown in FIG. 7. Mold core 55 canthen be drawn back, as shown in FIG. 8, for creating a larger moldcavity 22b for the introduction of material 34 from nozzle 28.Accordingly, article 12 is formed, as shown in FIG. 8, comprising twostructurally distinct portions formed from two distinct materials.

FIGS. 9 and 10 are indicative of another process which may be used withthe nozzle arrangement shown in FIGS. 1-4. In this process, a film orsheet 60 can be placed between female mold half 14 and male mold half 16for use as reinforcement, as a means for decorating the molded article,or as an insert for separation and the formation of two articles in onecavity. Once the mold is closed, injection can begin from both halves ofthe mold, as shown in FIG. 10, either simultaneously or sequentially. Assuch, sheet 60 is covered by injected materials 34 on one side and 44 onthe other side. The resultant article 12 has a material of differenttypes on each side of it, and if sheet 60 is used as a partition forseparation, mating elements of different materials are created.

Another embodiment of the instant invention is shown in FIGS. 11 and 12,wherein an article can be formed having abutting halves of differentmaterials. In this embodiment, nozzle 236 is positioned in mold half 216vertically offset from the positioning of nozzle 228 in female mold half214. A partition 260 is operable to be positioned in and retracted fromcavity 222 so as to divide cavity 222. As such, and referring to FIG.11, first material resin 244 is injected into first cavity portion 262of cavity 222. Partition 260 is then retracted and second material,resin 234, as shown in FIG. 12, is injected into second cavity portion264 of cavity 222. As an alternative to using partition 260, a meteredshot of a first material, resin 244, could be injected into cavity 222,followed by a second injection of a resin 234 to fill out the space ofcavity 222 and bond to first material, resin 244. Also, both materials244 and 234 could be injected simultaneously which would result inreduced time required to fill cavity 222, as well as a more simplifiednon-metered injection process.

In using the offset arrangement as shown in FIGS. 11 and 12, other typesof molded articles can be achieved by varying other parameters such asmold shape, timing, pressure, and viscosity (as discussed above). FIGS.13 and 14 show an example of using the offset design of FIGS. 11 and 12with a non-uniform shaped mold cavity 270. As shown in FIG. 13, moldcavity 270 is separated into an upper small portion 271 having a lesservolume than a lower large portion 272. A first material, resin 234, isinjected to fill upper portion 271, and this is followed by theinjection of a second material, resin 244 into lower portion 272, whichfills cavity 270, as shown in FIG. 14. As a result of this process andmold configuration, the article 212 produced, in its lower portion, hasa skin material of one characteristic and a core of anothercharacteristic. Different combinations of injection points, amounts, andtiming can be utilized to produce articles with various configurations.

Another alternative embodiment of this invention is shown in FIG. 15. Inthis instance, the offset layout of the nozzles as shown in FIGS. 11-14can be used for the injection molding of a large number of smallmonomaterial articles 312 via a multitude of closely spaced cavities322. With the arrangement as shown in FIG. 15, spacings as tight as themolded article size will allow can be achieved. As shown in FIG. 15, aplurality of cavities are injected from female mold half 314 via nozzles328 and a plurality of cavities 312 are injected from male mold half 316via nozzles 336. The offset nature of the plurality of sequentiallyspaced nozzles 328 and 336 enable the faces of the mold halves 314 and316 to be efficiently used with nearly adjacent spacing of the moldcavities 322. This arrangement liberates the design of the hot runnersand allows the use of standard nozzles and manifolds systems, withoutincreasing the distance between mold cavities, thereby capitalizing onthe area available for molding articles 312. This arrangement isparticularly advantageous when a mechanically actuated injection gate isto be used for the cavities 322. For example, many medical articlesrequire that the gate vestige be smoother than available with thermalgates, thus requiring mechanical gates. Such mechanically actuated gatesgenerally require room in excess of room requirements for thermal gates.The offset arrangement of the plurality of nozzles in this embodimentcreates more room, thereby satisfying the room requirement of themechanical gates.

FIG. 16 is indicative of another embodiment of this invention, wherein aco-injection nozzle 480 is used in female mold half 414 and is opposedby singular material injection nozzle 436, similar to those shown in theother embodiments, in male mold half 416. As an additional alternative,a co-injection nozzle could also be employed in the mold half 416 forinjecting two or more materials from male half 416. Any combination ofone material, two material or more than two material nozzles could beused in the mold halves configuration as shown in FIG. 16, to satisfythe manufacturing of the type of articles desired. As a consequence ofthe nozzles opposing each other in opposing mold halves, simplication ofthe hot runner 454 of the co-injection nozzle 480 can be achieved. Thatis, portions of the previously complex hot runner systems, for example,the hot runners for the normal nozzle types, can be moved into the malemold half 416 thereby creating room in female mold half 414 for the morecomplex hot runners used with co-injection nozzles 480.

In one example of the operation of a system as shown in FIG. 16, a firstamount of material 490 is injected from female mold half 414 andco-injection nozzle 480 into mold cavity 422. First material 490 isfollowed by a second material 444 from nozzle 436 positioned in the malemold half 416. Sequentially, a third material 492 is injected intocavity 422 from co-injection nozzle 480 which divides and further pushesmaterials 490 and 444 into cavity space 422 for filling the same. Thisis only one example of the injection combinations which are possibleusing the principles of this embodiment of this invention. That is,injections can be sequential or simultaneous, the nozzles can be of anyconfiguration, for example, opposed or offset, the injections can beindependently and precisely metered, timed, or otherwise effected, andmold movements can take place between or during the injections.

The primary object of this invention is to provide a system and methodfor injecting a plurality of resins into a mold cavity in a spaceefficient manner. Another object is to provide an injection system andmethod which uses simple nozzle and hot runner designs. Yet anotherobject is to provide an injection system and method wherein hot runnersand nozzles can be independently adjusted for each resin while suchsystem is space efficient. Still another object is to provide aninjection system and method which is simple in construction and canproduce parts with unique qualities. And still another advantage of thisinvention is that a space efficient single reesin injection system isprovided for efficiently molding a plurality of articles in amulti-cavity mold.

It is apparent that there has been provided in accordance with thisinvention a opposed gating injection system and process which fullysatisfies the objects, means, and advantages set forth hereinbefore.While the invention has been described in combination with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims.

What is claimed is:
 1. An injection molding process for forming a moldedmulti-layered plastic article from a plurality of materials,comprising:providing an injection molder having a first stationary moldhalf with a first molding surface and a second movable mold half with asecond molding surface wherein said molding surfaces are adapted tocooperate to form at least one mold cavity for forming said moldedplastic article, said cavity having a peripheral edge region; relativelymoving said first and second mold halves together along a first axis toform said mold cavity; injecting a first plastic material through saidfirst mold half along said first axis or parallel to said first axisinto said mold cavity through a first orifice from a first injectionmeans positioned in said first mold half; injecting a second plasticmaterial through said second mold half along said first axis or parallelto said first axis into said mold cavity while the first plasticmaterial is still in the fluid state through a second orificeunconnected with said first orifice from a second injection meanspositioned in said second mold half, wherein said second material isdifferent from said first material; and wherein said first and secondplastic materials are at least partially sequentially injected into saidcavity so that the first injected plastic is forced to the edge regionof said cavity to form substantially the entire edge region of themulti-layered article, and the second injected plastic forms theinterior of the multi-layered article with the first injected plasticsubstantially surrounding the second injected plastic.
 2. The processaccording to claim 1, wherein said first and second materials areinjected into said cavity along a first axis, said process furthercomprising the steps of placing a sheet means, said sheet means forseparating said molded article, between said first and second moldhalves in an orientation substantially transverse to said firstdirection and closing said mold halves on said sheet means.
 3. Theprocess according to claim 1, wherein said first mold half is a femalemold and said second mold half is a mold core, said process furthercomprising the steps of:positioning said mold core and female mold toform said mold cavity; injecting said first material into said moldcavity; repositioning at least one of said mold core and female mold andaltering the shape of said mold cavity; and injecting said secondmaterial into said mold cavity after the shape of said mold cavity hasbeen altered.
 4. The process according to claim 1, wherein saidinjection means are positioned substantially offset from each otheradjacent said mold cavity, said process further comprising the stepsof:placing a partition in said mold cavity and forming a first cavityportion and a second cavity portion, wherein said first injection meansis positioned for injecting said first material into said first cavityportion and said second injection means is positioned for injecting saidsecond material into said second cavity portion; and removing saidpartition after said first injection means injects said first materialand before or during said second injection means injects said secondmaterial.
 5. The process according to claim 1, wherein said firstinjection means is a coinjection nozzle and said second injection meansis a single material injection nozzle, said process further comprisingthe step of injecting a third material into said mold cavity from saidcoinjection nozzle positioned in said first mold half.
 6. The processaccording to claim 5, wherein said third material is different than saidsecond material.
 7. The process according to claim 5, wherein said thirdmaterial is the same as said second material.
 8. The process accordingto claim 1, wherein said cavity has a substantially non uniform crosssection comprising a first portion and a second portion, wherein saidfirst injection means is positioned to inject said first material intosaid first portion and said second injection means is positioned toinject said second material into said second portion, said processfurther comprising the steps of:injecting said first material into saidfirst portion prior to injecting said second material into said secondportion; allowing said first material to flow into said second portion;delaying the injection of said second material into said second portionuntil said first material passes by said second injection means in saidsecond portion; and injecting said second material into said firstmaterial in said second portion and pushing said first materialoutwardly toward said molding surfaces, said second material forming acore of a portion of said article formed by said second portion of saidcavity.
 9. The process according to claim 1, wherein said first materialis injected from a location substantially directly opposite the locationfrom which said second material is injected.
 10. The process accordingto claim 9, including injecting a first plastic material into said moldcavity from a first injection means which includes a first injectionunit and first injection nozzle, including the step of positioning thefirst injection unit and first injection nozzle substantially in line.11. The process according to claim 10, including injecting a secondplastic material into said mold cavity from a second injection meanswhich includes a second injection unit and second injection nozzle,including the step of positioning the second injection unitsubstantially perpendicular to the second injection nozzle.
 12. Theprocess according to claim 11, including the step of positioning thefirst injection unit and first injection nozzle on the same horizontalplane, and positioning the second injection unit spaced vertically fromthe second injection nozzle.
 13. The process according to claim 1,including providing a manifold for at least one of said plasticmaterials, and heating at least one of said plastic materials in saidmanifold prior to injection into said cavity.
 14. The process accordingto claim 13, including providing a manifold for the first and secondplastic materials, and heating said plastic materials in said manifoldsprior to injection into said cavity.
 15. An injection molding processfor forming molded plastic articles, comprising:providing an injectionmolder having a first stationary mold half having a first moldingsurface and a second movable mold half having a second molding surfacewherein said molding surfaces are adapted to cooperate to form aplurality of mold cavities for forming a plurality of said moldedplastic articles; relatively moving said first and second mold halvestogether along a first axis said mold cavities; injecting a firstplastic material through said first mold half along said first axis orparallel to said first axis from a first injection means positioned insaid first mold half into each mold cavity of a first group of said moldcavities; and injecting said first plastic material through said secondmold half along said first axis or parallel to said first axis from asecond injection means positioned in said second mold half into eachmold cavity of a second group of said mold cavities.
 16. The processaccording to claim 15, wherein said second injection means aresubstantially offset from said first injection means and said steps ofinjecting occur substantially simultaneously.
 17. An injection moldingprocess for forming a molded multi-layered plastic article from aplurality of materials, comprising:providing an injection molder havinga first stationary mold half with a first molding surface and a secondmovable mold half with a second molding surface wherein said moldingsurfaces are adapted to cooperate to form at least one mold cavity forforming said molded plastic article, said cavity having a peripheraledge region; relatively moving said first and second mold halvestogether along a first axis to form said mold cavity; injecting a firstplastic material through said first mold half along said first axis orparallel to said first axis into said mold cavity through a firstorifice from a first injection means positioned in said first mold half;injecting a second plastic material through said second mold half alongsaid first axis or parallel to said first axis into said mold cavitywhile the first plastic material is still in the fluid state through asecond orifice unconnected with said first orifice from a secondinjection means positioned in said second mold half, wherein said secondmaterial is different from said first material; and wherein said firstand second plastic materials are At least partially sequentiallyinjected into said cavity to form a multi-layered plastic article.